Kohlrabi is a quick-growing, tasty vegetable that is a member of the cabbage family despite its tuber appearance. The seeds should be sowed in early spring, and depending on the variety, they will be ready to harvest in 40 to 60 days. For a continuous supply of fresh kohlrabi, plant them at two to three week intervals until late summer.
Amend the soil in fall. Spread a two to four inch layer of organic compost and add four to six cups of all purpose fertilizer per 100 square feet. Then turn the soil to a depth of six inches.
Check your amended soil's pH with a pH meter. Kohlrabi prefers acidic soil. If your soil's pH is below 6.3, add lime to raise it.
Plant your kohlrabi seeds. They should be planted one-quarter to one-half inch deep and two to five inches apart in rows that are one foot apart.
Spread a two to four inch layer of plastic mulch around (but not on top of) your kohlrabi plants. This will help them retain moisture and prevent the stems from becoming tough and woody.
Water your kohlrabi plants frequently. They need one to two inches of water per week.